Glass fiber reinforced lightweight plastic panels have found many applications in the automotive industry in recent years. These include the use of either short glass fibers or long strands of glass fibers. In the application of short glass fibers, both milled and chopped glass fibers are used for the reinforcement of thermoplastics or thermosets. On the other hand, long glass fiber strands are frequentl used in the form of glass fiber mats. These mats can be used as reinforcement in a plastic part by either injection molding a thermoplastic material or a RIM (reaction injection molding) type thermoset material into it.
Glass fiber mat reinforced plastic panels potentially can be used in either interior applications or exterior applications on an automobile. For instance, they can be used as load floors or seat backs in interior applications or body panels in exterior applications. The rigidity and strength of a glass fiber mat reinforced plastic panel are superior when compared to their steel counterparts. However, one drawback of this type of reinforced panels is that even though lighter than steel, their weight is still substantial because of the density of the thermoplastic or thermoset material used. This high density becomes more of a problem in some applications where both high strength and lightweight qualities are desired. For instance, in the application of an automobile headliner or interior door trim panels, a candidate material must have both the rigidity and the lightweight properties.
Many interior trim panels used in an automobile require shaping in a forming process. An ideal candidate for such applications should also be easily shapable or formable.
It is therefore an object of the present invention to provide a method of molding a laminated foamable sheet which can be used to shape glass fiber mat reinforced low density foam panels.
It is another object of the present invention to provide a method of molding a laminated foamable sheet so that lightweight automotive trim panels may be manufactured.
It is yet another object of the present invention to provide a method of molding a laminated foamable sheet such that a laminated foamable sheet expands in a heated mold to assume the shape of a cavity.